Oriented strand board (OSB) is an engineered wood product made by layering wood strands in specific orientations and binding them together with resin.
It is commonly used as a subflooring material but is more susceptible to water damage than plywood, making it essential to waterproof for outdoor use.
Waterproofing OSB can help prevent water from penetrating the surface and causing damage, extending the project’s life and saving money on repairs and replacements.
We’ll explore the steps you need to take to ensure your OSB is waterproof and will stand up to the elements.
Understanding OSB: Basics and Characteristics
OSB is made of small wood strands arranged in specific orientations and bonded with a synthetic resin. This process creates a strong and durable material that can withstand heavy loads and pressure. In construction projects, OSB is commonly used for subflooring, roofing, and wall sheathing. It’s also used in the furniture industry for its affordability and versatility.
OSB is available in different thicknesses, sizes, and grades. The thickness of OSB can range from 7/16 inch to 1 1/8 inch, and the sizes can range from 4 feet by 8 feet to 4 feet by 10 feet.
The grade of OSB determines its strength and durability, with higher grades being stronger and more moisture-resistant.
Differences between OSB and plywood
OSB and plywood are engineered wood products commonly used in construction projects. However, there are several differences between the two materials.
Plywood is made of thin wood veneers glued together with synthetic resin. Plywood is more expensive than OSB and has a smoother surface. Plywood is also more moisture-resistant and is often used in areas prone to water damage.
On the other hand, OSB is made of small wood strands arranged in specific orientations and bonded with synthetic resin.
OSB is more affordable than plywood and has a rougher surface. OSB is also more susceptible to moisture damage than plywood and requires proper waterproofing for outdoor use.
What Happens to OSB if it Gets Wet?
OSB is susceptible to moisture damage, and if it gets wet, it can lead to several problems.
Moisture can cause OSB to swell, warp, and rot, leading to a shortened lifespan and potential safety hazards. Moisture can also attract pests and insects, leading to further damage and potential health hazards.
Why Waterproofing is Essential for OSB
Waterproofing is essential for OSB to protect it from moisture damage and prolong its lifespan. Several techniques for waterproofing OSB include painting, sealing, and using membranes.
Waterproofing your OSB will help prevent water from penetrating the surface and causing damage, ensuring your project is strong and durable for years.
The Need for Waterproofing OSB
OSB is a versatile and affordable material, but it’s susceptible to moisture damage, so it’s important to waterproof it to avoid potential damage and cost implications.
Why It’s Necessary to Waterproof OSB
Water is one of the most significant threats to OSB, and if left unprotected, it can cause several problems.
Moisture can cause OSB to swell, warp, and rot, leading to weakened material that can be a safety hazard. Additionally, moisture can attract pests and insects, leading to further damage and potential health hazards.
Waterproofing your OSB is essential to protect it from moisture damage and ensure its longevity. OSB can be exposed to the elements without waterproofing, including rain, snow, and humidity.
Over time, this exposure can cause the material to break down and deteriorate, leading to costly repairs and potential safety hazards.
The Potential Damage and Cost Implications if OSB isn’t Waterproofed
If OSB isn’t waterproofed, it can lead to several problems. Moisture can cause the material to swell and warp, which can lead to weakened material that can be a safety hazard.
Additionally, moisture can attract pests and insects, leading to further damage and potential health hazards.
If OSB is not waterproofed, it can lead to costly repairs and replacements. Moisture damage can cause the material to break down and deteriorate, weakening structural integrity and the need for costly repairs. In some cases, the damage may be so severe that the material needs to be entirely replaced, leading to further costs and delays.
Do You Need to Waterproof OSB?
The short answer is yes. Waterproofing is essential if you’re using OSB in an outdoor project or in an area exposed to moisture.
OSB can quickly deteriorate without proper protection, leading to a shortened lifespan and potentially costly repairs.
Even if you’re using OSB indoors, waterproofing can help protect it from humidity and other moisture-related problems.
Waterproofing Techniques for OSB Sheets
Step-by-Step Guide on How to Waterproof OSB Sheets
Clean the surface: Start by cleaning the surface of the OSB sheet. Remove any dirt, debris, or loose particles using a broom or brush.
Sand the surface: Use sandpaper to smooth the surface of the OSB sheet. This will help ensure that the waterproofing material adheres properly to the surface.
Apply primer: Apply a primer to the surface of the OSB sheet. The primer will help the waterproofing material adhere to the surface and strengthen the bond.
Apply waterproofing material: Apply the waterproofing material to the surface of the OSB sheet using a brush or roller. Ensure that the entire surface is covered with the material.
Apply a second coat: Once the first coat has dried, apply a second coat of waterproofing. This will provide an extra layer of protection against moisture.
Allow to dry: Allow the waterproofing material to dry completely before continuing your project.
How to Apply an OSB Waterproof Membrane
Another option for waterproofing OSB sheets is to apply an OSB waterproof membrane. Here’s how to do it:
Clean the surface: Clean the surface of the OSB sheet as described above.
Cut the membrane: Cut the OSB waterproof membrane to the appropriate size for your project.
Apply adhesive: Use a trowel to the surface of the OSB sheet.
Apply the membrane: Carefully apply the OSB waterproof membrane to the surface of the OSB sheet, ensuring that it is smooth and free from wrinkles or bubbles.
Press down: Use a roller to press down on the membrane, ensuring that it adheres properly to the surface of the OSB sheet.
Seal the edges: Seal the edges of the membrane using a sealant or waterproof tape to prevent water from seeping in.
How to Seal the Edges of OSB
Sealing the edges of OSB is essential to prevent water from seeping in and causing damage. Here’s how to do it:
Clean the edges: Clean the edges of the OSB sheet using a brush or broom.
Apply a sealant: Apply a sealant to the edges of the OSB sheet using a brush or roller. Ensure that the entire edge is covered with the sealant.
Apply a second coat: Once the first coat has dried, apply a second coat of sealant to the edges of the OSB sheet.
Allow to dry: Allow the sealant to dry completely before continuing your project.
Waterproofing OSB Floors
Step-by-Step Guide on How to Waterproof an OSB Floor
Prepare the surface: Start by preparing the surface of the OSB floor. Remove any dirt, debris, or loose particles using a broom or brush.
Sand the surface: Use sandpaper to smooth the surface of the OSB floor. This will help ensure that the waterproofing material adheres properly to the surface.
Apply primer: Apply a primer to the surface of the OSB floor. The primer will help the waterproofing material adhere to the surface and strengthen the bond.
Apply waterproofing material: Apply the waterproofing material to the surface of the OSB floor using a brush or roller. Ensure that the entire surface is covered with the material.
Apply a second coat: Once the first coat has dried, apply a second coat of waterproofing. This will provide an extra layer of protection against moisture.
Allow to dry: Allow the waterproofing material to dry completely before continuing your project.
The best coating for an OSB floor is a polyurethane sealer. This type of sealer creates a strong, protective barrier against moisture and is resistant to wear and tear.
Sealing an OSB floor is essential to prevent moisture from seeping in and causing damage.
Specific Waterproofing Products for OSB
Regarding waterproofing OSB, various products on the market can help protect your OSB from moisture and extend its lifespan.
OSB Waterproof Paint
OSB waterproof paint is popular for many people looking to waterproof their OSB. It is a type of paint specifically designed to resist moisture and can be applied to OSB surfaces using a brush or roller.
One of the benefits of using OSB waterproof paint is that it can also add color to your OSB surface, making it more visually appealing. This type of paint usually requires two coats to achieve maximum protection.
OSB Waterproof Sealer
Another popular product for waterproofing OSB is the OSB waterproof sealer. This type of sealer is a clear liquid that is applied to the surface of the OSB using a brush or sprayer.
It works by penetrating the pores of the OSB, creating a protective barrier that resists moisture.
One of the benefits of using an OSB waterproof sealer is that it won’t change the appearance of your OSB surface and is easy to apply.
Thompson Water Seal
Thompson’s Water Seal is a widely recognized waterproofing solution for outdoor structures like decks and fences. However, its versatility extends to waterproofing OSB surfaces as well.
Available in clear and tinted variants, this product can be conveniently applied using a brush or sprayer. It operates by infiltrating the OSB surface and establishing a barrier resistant to water and UV rays, usually requiring two coats for optimal defense.
While exploring this product, learning how to seal wood for outdoor use would be beneficial, expanding your understanding of various wood preservation methods.
AFM Safe Seal Plywood OSB Sealer
The AFM Safe Seal Plywood OSB Sealer is another popular product for waterproofing OSB. This sealer is designed for plywood and OSB surfaces and is VOC-free, making it a great choice for those sensitive to strong odors.
This product is a clear liquid that is applied using a brush or sprayer and works by penetrating the surface of the OSB to create a waterproof barrier.
Which is the Best Waterproof Paint for OSB?
Several factors must be considered when choosing the best waterproof paint for OSB. One of the most important factors is the level of protection that the paint provides.
Look for a paint specifically designed to resist moisture and has high waterproofing protection. You should also consider the color of the paint and whether it will complement the look of your OSB surface.
What is a Good Waterproof Sealer for OSB?
Several options are available if you’re looking for a good waterproof sealer for OSB. Look for a sealer specifically designed for OSB surfaces and provides high protection against moisture.
You should also consider the application method, as some sealers are easier to apply than others. Lastly, consider the color of the sealer and whether it will change the appearance of your OSB surface.
Waterproofing OSB for Exterior Use
The most important details for sealing OSB for exterior use are to choose the right type of OSB, apply a waterproof membrane or coating to the surface of the OSB, and follow the manufacturer’s instructions when applying a waterproof membrane or coating.
Best practices for using OSB in an exterior setting include making sure the OSB is properly installed, keeping the OSB as dry as possible, and choosing a waterproof coating or sealant that will withstand the elements and provide long-lasting protection.
How Long Will OSB Last Outside?
The lifespan of OSB used outdoors can vary depending on the quality, installation method, and moisture exposure. However, properly installed and waterproofed OSB can last up to 30 years.
When selecting OSB for outdoor use, it is important to choose exterior-grade OSB designed to withstand moisture exposure and provide adequate protection from the elements.
If not properly waterproofed or maintained, it can deteriorate quickly and lead to costly repairs or replacement.
DIY Waterproofing Techniques
One popular DIY option for waterproofing OSB is to use a product called Flex Seal.
Flex Seal is an effective liquid rubber sealant for waterproofing OSB. Its durable, long-lasting rubberized coating creates a watertight barrier when sprayed directly onto the surface of the OSB.
To apply Flex Seal, clean the surface of the OSB and spray the product evenly onto the entire area.
Follow the manufacturer’s instructions carefully, allowing the product to dry completely before exposing it to water. Yes, you can use Flex Seal on OSB for effective waterproofing.
Another DIY option for waterproofing OSB is PVA (polyvinyl acetate) glue.
You can use PVA glue as a DIY option to waterproof OSB. It’s a water-based adhesive that creates a water-resistant coating on the OSB surface. PVA glue is affordable and easy to apply, and you can find it at most hardware stores.
To waterproof OSB with PVA glue, dilute it with water and apply it evenly to the OSB surface using a paintbrush or roller.
Let it dry completely before applying a second coat for added protection. PVA glue can seal OSB, but it’s only water-resistant, not completely waterproof.
OSB Pricing and Buying Guide
As mentioned above, the current price for 1/2 inch OSB ranges from $34 to $51 per sheet. However, prices may vary depending on the vendor and the location.
Comparing the selling price for 1/2 inch OSB at Lowe’s to other vendors, it is advisable to research local home improvement stores or lumberyards in your area. However, according to a quick comparison of prices on Lowe’s and Home Depot websites, both stores have similar prices for OSB, with some slight variations.
A waterproof OSB board can cost more than a regular OSB due to its added features. The cost of waterproof OSB can range from $50 to $100 per sheet, depending on the brand, thickness, and other factors.
It is essential to check the product specifications to ensure that the OSB meets your requirements for water resistance.
In summary, the current price range for 1/2 inch OSB is $34 to $51 per sheet, and the cost of waterproof OSB can range from $50 to $100 per sheet, depending on the brand and thickness. When comparing prices, it is advisable to check the prices of various vendors in your area to determine the best deal.
Frequently Asked Questions
How does waterproof OSB compare with regular OSB in terms of performance?
OSB is a wood panel made from strands of wood bonded together using adhesive resins and heat. Regular OSB is not waterproof and is typically used for indoor applications. Waterproof OSB, also known as OSB/3, has a special coating that makes it resistant to moisture and suitable for outdoor use, such as roofing and flooring.
Does waterproofing extend the lifespan of OSB?
Waterproof OSB performs better than regular OSB when it comes to resisting moisture. It can endure exposure to water and moisture, making it more appropriate for areas where regular OSB would not be suitable. It is less prone to swelling, warping, and delamination, which can lead to structural damage and affect its durability. Waterproofing OSB extends its lifespan, improving its overall performance and making it a better long-term investment.
What can happen to OSB when it gets wet?
Moisture can damage OSB, causing it to swell, warp, weaken, and develop fungal growth. This can also lead to discoloration and delamination. Waterproof OSB is made to resist these issues.
Can you put polyurethane on OSB?
Polyurethane is a sealant that can be used on OSB to improve its resistance to moisture. This clear, waterproof coating can be applied to regular and waterproof OSB to seal gaps and prevent water penetration. Applying polyurethane only to clean and dry OSB surfaces is important to achieve maximum effectiveness.
Which is more resistant to water: plywood or OSB?
Plywood and OSB are popular construction options, but OSB has a slight edge over plywood in moisture resistance due to its stronger, more uniform surface made from smaller wood strands. Both materials can benefit from waterproofing. Plywood absorbs moisture quicker but also dries quicker, and returns to almost its exact shape when dry. OSB shows more deformities after a wetting and drying cycle and is less forgiving when exposed to rain.
Is there a certain type of sealant that is best for OSB?
When sealing OSB, choose the best sealant based on the moisture resistance required.
Silicone sealant is ideal for flexible areas like windows and doors, an acrylic sealant is easy to apply and paintable for interior use, and polyurethane sealant provides the best waterproofing.
Choose a compatible sealant and follow the manufacturer’s instructions for best results.
What are some tips for maintaining the waterproofing of OSB?
To keep OSB waterproof, take precautions and follow specific maintenance practices. Store it in a dry, covered area, seal all joints and edges during installation, inspect and maintain the surface regularly, and repair or replace any damaged areas immediately.
What are the top-rated products to use for waterproofing OSB?
Regarding waterproofing OSB, there are a few top-rated products to consider. These include liquid-applied membrane, self-adhering membrane, and peel-and-stick tape.
Liquid-applied membrane is a liquid coating that can be rolled or sprayed to create a flexible, waterproof layer.
Self-adhering membrane comes with a self-adhesive backing for easy installation and protection against moisture. Peel-and-stick tape is a quick and simple solution for sealing seams and joints in smaller areas.
Final Thought
We’ve covered all the bases on waterproofing, storing, and installing OSB, the various types of sealants, and the most effective ways to waterproof this versatile material.
Properly sealing and maintaining your OSB is paramount in protecting it from moisture.
Prevention is always better than repairing damage when preserving your OSB investment.
Remember these recommendations; you’ll have a strong, waterproof OSB for years. You might even impress your loved ones with your newfound OSB expertise!
